Why Bill Kristol left Fox News

11/1/13 7:16 AM EDT

Bill Kristol, the editor and publisher of The Weekly Standard, ended a decade-long run as Fox News contributor this summer two years after he and Roger Ailes got into a disagreement that had a cooling effect on their relationship, sources with knowledge of their relationship told POLITICO.

In 2011, the Fox News chief asked Kristol to take a negative stance toward a certain individual, effectively helping Ailes in his effort to give that person a bad reputation, the sources said. Kristol refused to get involved in Ailes' personal arguments and, as a result, there was a "coolness" between the two going forward. Though the relationship remained cordial, Ailes felt he could no longer trust Kristol to be a team player.

Kristol's departure, which he announced in August, was due to a number of factors: Kristol was less central to Fox News programming during the 2012 election than he had been in previous cycles. He was also appearing less frequently on Fox News Sunday, due in part to the show's desire to have more variety on its panel. The network's plans to hire columnist George Will, another conservative columnist, may have played a role.

But the disagreement, while not directly responsible for the break, had a notable effect on the relationship between the two men, and may have been a factor. At the end of 2012, Kristol and Ailes began an ongoing discussion about his future at the network. Both agreed that he had become less central to the network, and after several months the two parties decided not to renew the contract.

Fox News spokespeople Irena Briganti and Dana Klinghoffer did not respond to a request for comment regarding Kristol's departure or the 2011 disagreement.

Kristol, who said he was "treated nicely" at Fox News, declined to comment on the incident. "I had a great ten years at Fox, but it's also been fun being a free agent," he told POLITICO. "Fox seems to be doing great without me being on all the time, I hope I'm doing ok being on all the other networks some of the time."

Indeed, Kristol has become a coveted free agent since leaving Fox News. He has made multiple appearances on ABC's "This Week" (where he was a panelist in the 1990s) and NBC's "Meet The Press" (he will join the roundtable again this Sunday). He has also made multiple appearances on CNN's "Crossfire" and on MSNBC's "Morning Joe."

"I enjoy the flexibility of being a free-agent and the variety of the shows, which have been stimulating," he said. "It's also fun getting a rise out of the MSNBC viewers."

Kristol hasn't severed ties with Fox News completely. He appeared on Fox News Sunday's roundtable on Sept. 15 -- but this time as a guest, not as a contributor.

Kristol said it was very possible that he could strike a deal with another network in the months ahead.

"I think I will talk to some of the other networks. I'll have those conversations over the next two or three to months," he said. "For now, it's fun to be able to discuss and argue with different people in different forums."

Roger doesn’t recall a specific or negative incident — he likes Bill and doesn’t have an issue with him. We made a lot of changes at the network and had been talking to George Will for some time. Bill’s contract ran out in the midst of this and at that point, we were fine with him appearing on other networks/declined to renew it."